1. Technical Field of the Invention
The present invention generally relates to optical burst switching (“OBS”) networks. More particularly, and not by way of any limitation, the present invention is directed to a method and apparatus for scheduling transmission of data bursts in such networks.
2. Description of Related Art
In burst switching technology, such as, in particular, optical burst switching (“OBS”) technology, data bursts (“DBs”), each of which is made up of multiple packets, are switched optically at core nodes, or routers, in the OBS network. A small control packet, called the Burst Header Packet (“BHP”) travels an offset time ahead of each DB along the same DB route and configures the optical switch for the duration of the DBs at the core node. In short, each BHP travels an offset time ahead of its associated DB and establishes a path for the DB.
Contention may occur between multiple PRP attempting to traverse the same link within the network. Several distributed scheduling algorithms with different behaviors and complexities have been suggested for use in OBS networks. OBS network performance can be defined in terms of burst loss ratio, which is the percentage of bursts lost during scheduling. Existing scheduling algorithms are inefficient and result in high burst loss ratio in OBS systems.
The problem of scheduling data bursts in OBS networks is to be solved in such a way that can optimize the resource utilization and improve scheduling performance. A well known solution is the Just-Enough-Time (“JET”) scheduling scheme, which is an example of a scheduling solution that schedules DBs on a one-by-one basis immediately after the bursts or their associated burst header packets (“BHPs”) are received. Since the scheduling decision is based on only the current burst, on a long-term basis, this solution can lead to a sub-optimal scheduling performance and relatively less efficient resource utilization. Further, the existing solutions, such as JET, that aim to provide service differentiation either have a problem of fairness in resource allocation or impose additional complexity.